Personal care absorbent articles, such as disposable diapers, are typically configured to acquire and retain the body fluids for which the articles were designed, avoid excessive leakage of waste materials from the article and to minimize the amount of any residue which migrates from the absorbent material onto the skin of a wearer. For example, diapers for infants are typically designed to accept large volumes of urine in multiple doses which can measure 60-100 ml per dose. Such diapers often require the use of high absorbency, superabsorbent particles to provide the needed absorbent capacity. Typically, the particles are blended with woodpulp fibers to create an absorbent matrix. The matrix, however, is often unable to adequately contain the superabsorbent particles. As a result, dry particles can escape from the article prior to use, and wet particles can migrate from the absorbent matrix to leave an unsightly gel on the skin of the wearer.
Attempts to alleviate the loss of superabsorbent particles and the migration of superabsorbent gel have employed various types of barrier materials to shield the superabsorbent material from the wearer's skin. For example, nonwoven fabrics composed of meltblown polypropylene fibers have been used as a "wrap" about an absorbent core to contain superabsorbent particles within the core. The generally hydrophobic nature of the polypropylene however, requires that surfactants be employed to minimize the resistance to the penetration of aqueous liquids therethrough. The surfactant must be permanently bound to the nonwoven fabric. Otherwise, the surfactant can be washed away after one or two doses of liquid, and subsequent doses of liquid may undesirably be repelled by the fabric. Although meltblown nonwovens can have excellent integrity and particulate retention properties, the nonwovens can be costly to produce.
To provide desired containment of both wet and dry superabsorbent particles, crepe-wadding or tissue has been employed as a lower cost alternative to meltblown nonwovens. Different types of crepe-wadding, such as forming tissue and barrier tissue, have been employed to produce a combination of properties in absorbent articles. Forming tissue is typically a low basis weight, high porosity wadding employed as a substrate onto which a batt of woodpulp fluff fibers are formed in an airlaying process. Designed to allow the passage of a high volume rate of air flow therethrough, the forming tissue has large numbers of large pores which provide for a low resistance to airflow but are unable to adequately restrain the movement of relatively smaller superabsorbent particles. As a result, such forming tissues have not provided a sufficient barrier to superabsorbent migration. To address this problem, barrier tissues have been configured with small pores to better contain the superabsorbent particles. The barrier tissues have a low porosity which can be obtained by increasing the tissue basis weight and by modifying the fiber content to create increased fiber coverage. Although the barrier tissue was able to reduce the migration of superabsorbent, its low porosity restricted its versatility and necessitated the use of more complicated manufacturing processes.
Thus, conventional absorbent articles, such as those described above, have required more complicated manufacturing processes and more complex constructions to provide adequate performance. Despite the development of absorbent structures of the types surveyed above, there remains a need for absorbent structures which incorporate improved component layers having a high resistance to the migration of particulate superabsorbent material as well as a high permeability to the passage of air.